I've just discovered the ~/.gnome2/nautilus-scripts folder.

If you put a script in there, it appears on the right-click menu of the Nautilus file manager. The name of the script file is reflected in the menu entry name. It looks really nice if the script name has spaces and proper capitalisation.

You can make this more elegant by keeping a master script in your usual scripts folder and using symbolic links pointing back to the master script to create the menu items by name. The master script should do a case-esac switch on the menu item name to invoke whatever-you-want.